[ubuntu-uk] Preference for wifi hotspot to home router

[adrian at just-contact.me.uk]

I have a particularly annoying incidence where my neighbour has 
installed a BT router and since then we often get our ubuntu install 
giving the BT hotspot priority over out TalkTalk router, despite that 
our router has the setting to connect to when in range and there is no 
link to bt routers in the past. Is it best to find the mac address of 
the neighbour and block it or something else? I would rather not block 
BT routers in case I use home router access at other's homes using their 
home (not hotspot) access.
Many Thanks
Adrian